Ascorbic Acid Oral Solution
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
1 DEFINITION
Ascorbic Acid Oral Solution is a solution of Ascorbic Acid in a hydroxylic organic solvent or an aqueous mixture thereof. It contains NLT 90.0% and NMT 110.0% of the labeled amount of ascorbic acid (C6H8O6).
2 IDENTIFICATION
2.1 A.
Sample solution: A volume of Oral Solution equivalent to 40 mg of ascorbic acid
Analysis: To the Sample solution add 4 mL of 0.1 N hydrochloric acid, then 4 drops of methylene blue TS, and warm to 40°.
Acceptance criteria: The deep blue color becomes appreciably lighter or is completely discharged within 3 min.
2.2 B.
Sample solution: A volume of Oral Solution equivalent to 20 mg of ascorbic acid
Analysis: To the Sample solution add 15 mL of trichloroacetic acid solution (1 in 20). Add 200 mg of activated charcoal, shake the mixture vigorously for 1 min, and pass through a small fluted filter, returning the filtrate, if necessary, until clear. To 5 mL of the filtrate add 1 drop of pyrrole, agitate gently until dissolved, then heat in a bath at 50°.
Acceptance criteria: A blue color develops.
3 ASSAY
3.1 PROCEDURE
Sample solution: Transfer a volume of Oral Solution equivalent to 50 mg of ascorbic acid, previously diluted with water if necessary, to a 100-mL volumetric flask. Add 20 mL of metaphosphoric-acetic acid TS, dilute with water to volume, and mix.
Blank: A mixture of 5.5 mL of metaphosphoric-acetic acid TS and 15 mL of water
Titrimetric system
(See Titrimetry (541).)
Mode: Direct titration
Titrant: Standard dichlorophenol-indophenol VS
Analysis: Transfer a volume of the Sample solution, equivalent to 2 mg of ascorbic acid, into a 50-mL conical flask. Add 5 mL of metaphosphoric-acetic acid TS, and titrate with Titrant until a rose-pink color persists for at least 5 s. Correct for the volume of the Titrant consumed by the Blank.
Calculate the percentage of ascorbic acid (C6H8O6) in the portion of Oral Solution taken:
Result = {[(VS - VB) × F]/W} x 100
VS = Titrant volume consumed by the Sample solution (mL)
VB = Titrant volume consumed by the Blank (mL)
F = concentration of Titrant in terms of its equivalent of ascorbic acid (mg/mL)
W = nominal amount of ascorbic acid taken for Analysis (mg)
Acceptance criteria: 90.0%-110.0%
4 OTHER COMPONENTS
ALCOHOL DETERMINATION, Method (611) (if present): 90.0%-110.0% of the labeled content of alcohol (C2H5OH)
5 ADDITIONAL REQUIREMENTS
PACKAGING AND STORAGE: Preserve in tight, light-resistant containers.
LABELING: Label Oral Solution that contains alcohol to state the alcohol content.
